Reducing energy waste and becoming more energy efficient is not just about consuming less, but designing better.

Building green is about designing energy-efficient and environmentally-friendly buildings, combining smarter energy management with sustainable construction. Following is a short overview of the various processes that are being used in the design of green buildings.

Creating environmentally sound and resource-efficient buildings

In Europe and the United States, the residential and tertiary sectors represent the largest source of directly achievable energy savings. In France, for example, figures published in February 2013 by the French Ministry of Ecology, Energy and Sustainable Development, revealed that these two sectors alone accounted for an astonishing 44% of final energy consumption.

Two options are available to reduce energy waste: either through the renovation of existing building stock with a view to optimizing energy efficiency (in France this is provided for by the “Grenelle I” bill from August 3rd, 2009, which passed into law a range of energy efficiency commitments taken by the State following a series of political meetings between associations, think tanks, companies and political parties); or through the construction of new, more sustainable buildings. One of the most prominent examples of what energy efficient renovation can achieve is the Edith Green-Wendell Wyatt Federal Building renovated by SERA Architects in Portland. Its structure was re-cladded to create a sleek façade to enhance energy conservation performance, roof mounted photovoltaic panels and a rainwater harvesting system were added improving its energy and environmental efficiency, strengthening the building’s “green” credentials. .

The USEnvironmental Protection Agency (EPA) defines green building, also referred to as green construction or sustainable building, as “the practice of creating structures and using processes that are environmentally responsible and resource-efficient throughout a building’s life-cycle” from construction and operation to maintenance and deconstruction.

Reducing energy use through intelligent design, using the most appropriate materials

Good thermal insulation prevents heat loss and is a quite simple way of cutting energy use. Thermal inertia can be achieved by using false ceiling panels, mineral wool or hemp insulation as well as double-glazing windows, thus mitigating the impact of outside temperature variations. Thermal bridges, also called cold bridges, essentially leaks in the insulation layer, can be avoided by putting in place external insulation, such as an “insulating mantle” made out of bricks and polystyrene. Additionally, a ground heat exchanger can be used to heat or cool down the ventilated air by using the earth’s thermal inertia. One example of smart design comes from Loreto Bay Mexico, one of North America’s largest sustainable urban developments, where an insulation technique was used based on compressing earth block walls reinforced with wire and parged with plaster, and attaching one to the other using recycled Styrofoam.

Insulation is a very efficient way of avoiding energy loss, but it is just one of many energy-efficient solutions that should be considered to find the most appropriate for the type of building, location and use.

Taking advantage of natural sunlight is another way of reducing energy used in heating and lighting. Buildings can be designed in a way that allows them to optimize sunlight by installing thermally efficient windows that face the sun as well as heat-absorbent materials. These so-called passive-energy housing solutions can be very effective at reducing the energy used in heating. A passive energy designed home can use as little as 15kWh of primary energy per m² per annum for heating and less than 120 kWh per m² per annum for overall energy use. The Law Center at the University of Baltimore, designed by Behnisch Architekten and Ayers Saint Gross, is a great example of passive energy design in which the need for artificial lighting was reduced by using wide windows that allowed the building to optimize natural daylight. The windows feature automated venetian blinds that will block solar penetration.

Designing thermally efficient buildings

Green construction also incorporates “active” ways of designing thermally efficient buildings; the premise here is to enable buildings to generate their own energy.

Solar photovoltaic and thermal technology, used to generate electricity and heat, has come leaps and bounds over the last ten years and today these technologies installed on the roof, in the vicinity of the building or even on the side of the building are more efficient, generating more energy, than ever before. The Bushwick inlet park in New York, designed by Kiss + Cathcart Architects, has a maintenance facility topped with a verdant roof, where a solar trellis generating 66.15 kWe, half of the building’s energy resources.

Ground and air-source heat pumps are another means of self-generating heat, while wind turbines provide an additional source of power. .The Rexel Innovation Centre at the BRE Innovation Park in Watford, in the UK, has been equipped by Rexel showcasing the benefits of a range of energy efficient and renewable energy technologies to home and building owners in a ‘real-life’ setting. The long-term goal of green construction is to create Plus-energy buildings , a term used in building design to describe a structure that produces more energy than it uses. The Vauban and Rieselfeld neighbourhoods in Freiburg im Breisgau in Germany, feature sustainable energy powered housing at the scale of a city (with 50 PlusEnergy houses). In France, in anticipation of future energy regulation, the NGO ‘Effinergie’ developed the BEPOS standard for buildings whose use of non-renewable primary energy is inferior to the amount of renewable energy they produce. And in the US, the U.S. Green Building Council has created the LEED certification for Leadership in Energy and Environmental Design in buildings.

This evolution in certifications and environmental standards for buildings is also a reflection of people’s changing attitudes towards saving energy and the desire for a healthier lifestyle As Boone Hellmann, architect at University of California in San Diego, puts it: “In the 1960-70s, it took massive amounts of energy to make people comfortable, and buildings became a hermetically sealed space. Now, we strive for equal indoor and outdoor balance—if there is enough ambient light, you don’t need artificial light. It’s a mutually beneficial system; you get to enjoy the outdoor elements and use less energy.”